html {
    width: 100%;
    height: 100%;
}
body {
    width: 100%;
    height: 100%;
    background-image: url("海.jpg");
    background-position: center center;
    background-repeat: no-repeat;
    background-size: cover;
}
.calculator {
    width: 100%;
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
}
.cal {
    width: 600px;
    height: 400px;
    background-color: rgba(255, 255, 255, 0.5);
    border-radius: 20px;
}
.cal h1 {
    font-size: 24px;
    text-align: center;
    margin-top: 60px;
    margin-bottom: 40px;
}

.cal .row {
    height: 50px;
    width: 100%;
    display: flex;
    justify-content: space-around;/*设置flex的原因就是要用这个*/
    align-items: center;
    font-size: 25px;
    font-weight: 900;
    margin: 10px;
}
#c1 {
    width: 400px;
    height: 45px;
    font-size: 23px;
    text-indent: 10px;
    border-radius: 10px;
}
#c2 {
    width: 400px;
    height: 45px;
    font-size: 23px;
    text-indent: 10px;
    border-radius: 10px;
}

.option input {
    width: 100px;
    height: 70px;
    display: block;
    font-weight: 900;
    font-size: 20px;
    color: rgba(255, 255, 255, 0.618);
    border-radius: 20px;
    background-color: rgba(251,114,153, 0.7);
}
.option {
    margin-top: 20px;
    display: flex;
    justify-content: space-around;
}
.clear {
    display: flex;
    justify-content: center;
    align-items: center;
}
.reset #up {
    width: 200px;
    height: 30px;
    background-color:rgba(0, 0, 0, 0.4);
    color: white;
    font-weight: 900;
    line-height: 30px;
    text-align: center;
    border-radius: 10px;
    border:none;
    margin-top: 20px;
    transition: all 0.618s;
}
#up:hover{
    background-color: rgba(251,114,153, 0.7);
}